/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.core;

import org.springframework.lang.Nullable;
import org.springframework.util.ObjectUtils;

import java.lang.reflect.Method;

/**
 * A common key class for a method against a specific target class,
 * including {@link #toString()} representation and {@link Comparable}
 * support (as suggested for custom {@code HashMap} keys as of Java 8).
 *
 * @author Juergen Hoeller
 * @since 4.3
 */
public final class MethodClassKey implements Comparable<MethodClassKey>
{

    private final Method method;

    @Nullable
    private final Class<?> targetClass;


    /**
     * Create a key object for the given method and target class.
     *
     * @param method      the method to wrap (must not be {@code null})
     * @param targetClass the target class that the method will be invoked
     *                    on (may be {@code null} if identical to the declaring class)
     */
    public MethodClassKey(Method method, @Nullable Class<?> targetClass)
    {
        this.method = method;
        this.targetClass = targetClass;
    }


    @Override
    public boolean equals(Object other)
    {
        if (this == other)
        {
            return true;
        }
        if (!(other instanceof MethodClassKey))
        {
            return false;
        }
        MethodClassKey otherKey = (MethodClassKey) other;
        return (this.method.equals(otherKey.method) && ObjectUtils.nullSafeEquals(this.targetClass, otherKey.targetClass));
    }

    @Override
    public int hashCode()
    {
        return this.method.hashCode() + (this.targetClass != null ? this.targetClass.hashCode() * 29 : 0);
    }

    @Override
    public String toString()
    {
        return this.method + (this.targetClass != null ? " on " + this.targetClass : "");
    }

    @Override
    public int compareTo(MethodClassKey other)
    {
        int result = this.method.getName().compareTo(other.method.getName());
        if (result == 0)
        {
            result = this.method.toString().compareTo(other.method.toString());
            if (result == 0 && this.targetClass != null && other.targetClass != null)
            {
                result = this.targetClass.getName().compareTo(other.targetClass.getName());
            }
        }
        return result;
    }

}
